176 AN AMAZING SIGHT 



ten or twelve minutes; and this migration continued 

 for three days, or, at all events, three days from the 

 first day I saw them, at a spot about two miles from 

 my home. I was amazed at their numbers, and it 

 was a puzzle to me then, and has been one ever since, 

 that a species thinly distributed over the immense 

 area of the Argentine pampas and Patagonia could 

 keep to that one line of travel over that uniform 

 green, sea-like country. For, outside of that line, not 

 one bird of the kind could anywhere be seen; yet 

 they kept so strictly to it that I sat each day for 

 hours on my horse watching them pass, each flock 

 first appearing as a faint buff-coloured blur or cloud 

 just above the southern horizon, rapidly approaching 

 then passing me, about on a level with my horse's 

 head, to fade out of sight in a couple of minutes in 

 the north; soon to be succeeded by another and yet 

 other flocks in endless succession, each appearing 

 at the same point as the one before, following the 

 same line, as if a line invisible to all eyes except 

 their own had been traced across the green world 

 for their guidance. It gave one the idea that all 

 the birds of this species, thinly distributed over 

 tens of thousands of square miles of country, had 

 formed the habit of assembling, previous to migra- 

 tion, at one starting-point, from which they set 

 out in successive flocks of a medium size, in a 

 disciplined order, on that marvellous journey to 

 their Arctic breeding-grounds. 



Among the other species that swarmed in all the 

 marshy places the glossy ibis was the most abundant, 



